What to do about my 3 month old?

mine did that too and it always scared me when she choked. she may be teething. try giving her teething rings to chew on, they are harder than a pacifier. i know shes young but have you started baby cereal or jared baby food yet? if so put a little on the teething ring and put it in her mouth she will like the taste better than her hand. hope this helps good luck.